1. Preheat the oven to 400 degrees F.2. In a large skillet, heat 3 tablespoons oil. Add the onions and garlic; saute until onions are tender but not browned, about 5 minutes.3. In a 3-quart casserole, layer onion mixture, eggplant, zucchini and tomatoes with their juices. Sprinkle with basil and pour remaining oil over the mixture.4. Bake, covered, for 2 hours or until eggplant is very soft. Stir twice during baking. Add salt to taste. If vegetables have too much liquid, pour off some liquid into skillet. Bring to a boil; boil until reduced to a syrupy sauce. Pour over vegetables in the casserole.5. Garnish with quartered tomatoes and parsley. Serve hot or at room temperature.